Xbox Live cloud saves Gold-exclusive

Whereas other features of the upcoming dashboard update, such as "deeper Facebook integration" and enhanced Kinect support, will be available for all Xbox Live members, the cloud feature is (unsurprisingly) Gold-only.

One of the most exciting features of the upcoming Xbox 360 dashboard revamp is the introduction of cloud saves. The feature, referred to as both "Roaming Profiles" and "Cloud Profiles" by Microsoft, will allow you to take your "complete Xbox Live profile with you." Instead of using "Gamertag recovery," the new process will automatically transport your game progress, achievements, friends list, and Microsoft Points balance to any console you log in from.
Whereas other features of the upcoming dashboard update, such as "deeper Facebook integration" and enhanced Kinect support, will be available for all Xbox Live members, the cloud feature is (unsurprisingly) Gold-only.

An email clearly announces the Gold exclusivity

Microsoft didn't go into much detail on cloud storage when the feature was announced at E3, with some sites speculating that Microsoft would offer the feature free for all Xbox Live members--Gold and Free--in an effort to best PlayStation Network's take on cloud storage. (Cloud saves are only available for PlayStation Plus subscribers.)
Unfortunately, Microsoft has yet to date the upcoming the dashboard update, continually pointing to a "holiday" release.